The present invention relates generally to motion capture, and more particularly to capturing surface using motion marker data.
Motion capture systems are used to capture the movement of a real object and map it onto a computer-generated object as a way of animating it. These systems are often used in the production of motion pictures and video games for creating a digital representation of an object or person that is used as source data to create a computer graphics (“CG”) animation. In a typical system, an actor wears a suit having markers attached at various locations (e.g., small reflective markers are attached to the body and limbs). Appropriately placed digital cameras then record the actor's body movements in a capture volume from different angles while the markers are illuminated. The system later analyzes the images to determine the locations (e.g., spatial coordinates) and orientations of the markers on the actor's suit in each frame. By tracking the locations of the markers, the system creates a spatial representation of the markers over time and builds a digital representation of the actor in motion. The motion is then applied to a digital model in virtual space, which may be textured and rendered to produce a complete CG representation of the actor and/or the performance. This technique has been used by special effects companies to produce realistic animations in many popular movies.
However, limitations exist in motion capture systems. In particular, data derived from a motion capture session typically capture the movements of a rigid object, such as an extremity of an actor's body. For example, markers placed on an actor's forearm are used to develop data describing the motion of the forearm as a rigid object, connected to a hand and to an upper arm. The motion is therefore akin to that of a stick or rod, once the data have been processed. Hence, these data are sometimes referred to as a “skeleton” of the actor. However, missing are data describing the shape of the forearm, such as the tapering from elbow to wrist, and the cross-sectional contours at the different positions along the forearm.